Anyone who ever met Jane Jacobs or read her books couldn't help but be infected by her enthusiasms. She loved cities and celebrated the life that teems within them. She articulated better than anyone how the best ideas about making cities great come not from theories and master plans but from careful observation of what goes on around us. This was a startling, radical idea when she first proposed it in the 1950s and 60s, and it changed the way North Americans think about cities.